The present invention relates to a piezoelectric/electrostrictive material made of a porcelain obtained by firing, for example, to a piezoelectric/electrostrictive material used as an actuator or a sensor both assembled as an electromechanical transducer for positioning in precision machine tool or length control of optical path in optical instrument or in valve for flow rate control, etc. More particularly, the present invention relates to a piezoelectric/electrostrictive material suitably used in a very small sensor or a highly integrated very small actuator both used in an element for measurement of liquid property or very small weight.
As piezoelectric/electrostrictive materials, there have been known Pb(Zr,Ti)O3 (hereinafter referred to as PZT), BaTiO3, etc. They are in use in actuators, filters, various sensors, etc. PZT type piezoelectric/electrostrictive materials have been used mainly because they are superior in overall piezoelectric properties.
Pb contained in PZT, etc. is stabilized and essentially generates no problem caused by decomposition or the like. However, there are cases that a Pb-free material is required depending upon its application. Further, since Pb-containing porcelains such as PZT, PLZT [(Pb,La)(Zr,Ti)O3] and the like give rise to vaporization of small amount of Pb in high-temperature firing, they have had, particularly when used in applications requiring a thin or thick film, a problem that they hardly show stable properties owing to the compositional change during firing.
Meanwhile, BaTiO3 contains no Pb and offers a promising material for such a need. BaTiO3 viewed as a piezoelectric/electrostrictive material, however, is inferior in piezoelectric/electrostrictive properties to a PZT type material, and has seldom been used as an actuator or as a sensor. Therefore, the present invention has been made in view of the above-mentioned problems of the prior art and aims at providing a BaTiO3-based piezoelectric/electrostrictive material which is superior in piezoelectric/electrostrictive properties to conventional products and which can be suitably used in an actuator or a sensor, and a process for producing such a piezoelectric/electrostrictive material.